Most cited article - PubMed ID 37158246
αCharges: partial atomic charges for AlphaFold structures in high quality
The Protein Data Bank (PDB) is the largest database of experimentally determined protein structures, containing more than 230 000 experimentally determined structures. The chemical reactivity of proteins is based on the electron density distribution, which is usually approximated by partial atomic charges. However, because of the size and high variability, there is not yet a universal and accurate tool for calculating the partial atomic charges of these structures. For this reason, we introduce the web application PDBCharges: a tool for quick calculation of partial atomic charges for protein structures from PDB. The charges are calculated using the recent semi-empirical quantum-mechanical method GFN1-xTB, which reproduces PBE0/TZVP/CM5 charges. The computed partial atomic charges can be downloaded in common data formats or visualized online via the powerful Mol* Viewer. The PDBCharges application is freely available at https://pdbcharges.biodata.ceitec.cz and has no login requirement.
- MeSH
- Databases, Protein * MeSH
- Internet MeSH
- Protein Conformation MeSH
- Quantum Theory MeSH
- Proteins * chemistry MeSH
- Software * MeSH
- Static Electricity MeSH
- Publication type
- Journal Article MeSH
- Names of Substances
- Proteins * MeSH
PIN proteins establish the auxin concentration gradient, which coordinates plant growth. PIN1-4 and 7 localized at the plasma membrane (PM) and facilitate polar auxin transport while the endoplasmic reticulum (ER) localized PIN5 and PIN8 maintain the intracellular auxin homeostasis. Although an antagonistic activity of PIN5 and PIN8 proteins in regulating the intracellular auxin homeostasis and other developmental events have been reported, the membrane topology of these proteins, which might be a basis for their antagonistic function, is poorly understood. In this study we optimized digitonin based PM-permeabilizing protocols coupled with immunocytochemistry labeling to map the membrane topology of PIN5 and PIN8 in Arabidopsis thaliana root cells. Our results indicate that, except for the similarities in the orientation of the N-terminus, PIN5 and PIN8 have an opposite orientation of the central hydrophilic loop and the C-terminus, as well as an unequal number of transmembrane domains (TMDs). PIN8 has ten TMDs with groups of five alpha-helices separated by the central hydrophilic loop (HL) residing in the ER lumen, and its N- and C-terminals are positioned in the cytoplasm. However, the topology of PIN5 comprises nine TMDs. Its N-terminal end and the central HL face the cytoplasm while its C-terminus resides in the ER lumen. Overall, this study shows that PIN5 and PIN8 proteins have a divergent membrane topology while introducing a toolkit of methods for studying membrane topology of integral proteins including those localized at the ER membrane.
